PROJECT SUMMARY/ABSTRACT Social anxiety (SA) disorder is prevalent1, chronic2, and impairs quality of life3,4. Typical onset occurs in early adolescence2, when social relationships become more salient and complex. Thus, difficulty learning from nuanced interactions may potentiate SA6?11. Although SA is associated with suboptimal adaptive learning rates in non-social9?11 and uncertain/volatile contexts8,9, little is known about relations between SA and learning during symptom-eliciting social interactions with peers6,12?14. Moreover, in SA, social feedback is associated with dysregulated engagement of neural circuits implicated in salience and reward processing15?17, which are critical hubs for learning9,10,18?21. Despite this overlap, the neural mechanisms that support learning from social feedback remain relatively unexplored in SA. Treating deficits in social learning may diminish acute SA symptoms before they become chronic, thereby reducing the high societal cost of adult SA22. Progress towards this goal has been hindered by the limited extension of well-established computational methods to isolating the neural mechanisms of social learning. The proposed project addresses these limitations by pairing computational modeling with fMRI to determine the extent to which peer value, valence of peer feedback and volatility of peer feedback modulate the neural bases of social learning about peers and their relation to adolescent SA. The proposed project will study the behavioral and neural responses of adolescents (N=60; age 10-15yrs) with a range of SA to real-time social interactions with purported peers while undergoing an fMRI scan. Aims of this study are consistent with the NIMH strategic plan (Objective 1): defining the mechanisms of complex behaviors, specifically how environmental factors, such as social experiences, and neural mechanisms influence socially anxious behavior. The proposed study will determine neural circuits involved in complex social learning through interactions that are associated with SA. Such findings will provide novel treatment targets for SA. The proposed training plan, which consists of workshops, experiential learning, and mentorship, are designed to develop the applicant's expertise in computational modeling, neuroimaging and clinical assessment of SA disorder. The proposed study will take place within Temple University's clinical psychology program, which has a successful track record of conducting impactful NIMH-funded research and training research scientists.